Fwd: Rapid DHCP

[Genes MailLists]

On 07/30/2011 06:49 PM, Dan Williams wrote:

> 
> NM already keeps DHCP information around based on the network you're
> connecting to, so we don't need to ARP a bunch of servers just to
> determine whether the DHCP server we wanted is still there.  dhclient is

  Cool - so is NM already pretty optimal for the case when one sleeps a
laptop - and wakes it up in a new wireless domain?

  How does it know the dhcp server is still there when the laptop has
moved on?

> What's unique about the method described there is that the Mac
> configures the interface with the same IP address it previously had if
> the lease is still valid, while NetworkManager waits for the DHCP server
> confirm the lease.  So we could presumptuously configure the interface
> with the previous address from the lease and then only tear it down if
> the DHCP server fails or rejects the renewal.

  Probably best not to do this - as it can lead to duplicate IP's on the
network - even if briefly - wasn't something like this an issue with
some smartphones and princeton univ wifi - and led to them banning
android for whatever version had the problem ?

  http://code.google.com/p/android/issues/detail?id=11236

> 
> Of course, none of this helps if your DHCP leases are short, but it
> certainly helps if you put your laptop to sleep a lot and wake it up in
> the same location.
> 

 I tend to wake mine up in new locations a lot ... NM doesn't seem to
take very long to latch onto the new one.